It's been a while since I've played with BBC's but if I remember right, you can go beyond the .550" range before you need to worry about valve interference. I would try a COMP. Xtreme Energy cam. I have heard nothing but good things about them! As for a carb, you can easily step up into the 700 range. But, I would not suggest a double pumper in a heavy truck with a auto! GOOD LUCK!